The development of fetal behavioural states: a longitudinal study

In order to evaluate the development of fetal behavioural states a longitudinal study was performed on 35 healthy fetuses during the last trimester of pregnancy. Fetal heart rate (FHR), gross fetal body movements (FM), fetal eye movements (FEM), fetal breathing movements (FBM) and micturition were simultaneously studied at two-week intervals from 28 weeks gestation onwards. Well-defined fetal behavioural states were observed only after 36 weeks gestation. Between 28 and 36 weeks the quiet-activity cycle of FHR was always detected and some fetal biophysical activities seemed to become related around this cycle.     

Classification of fetal and neonatal heart rate patterns in relation to behavioural states

For the assessment of behavioural states in the human fetus, the fetal heart rate (FHR) pattern is one of the state variables. A statistical method is described to classify FHR patterns. FHR recordings were made between 38 and 40 wk gestation. The tachogram was averaged over 3-s intervals. For FHR segments of 3 min duration the parameters of an autoregressive-moving average (ARMA) model were estimated. Simulated FHR patterns, generated by using these estimated ARMA parameters, resembled real recordings. The ARMA parameters were used as features for a retrospective classification of the FHR segments, using a linear discriminant function. The classification by the above method was compared with an independent visual classification of the FHR patterns. The computer/observer classification agreement was 85% (kappa = 0.70). These data were compared with classification results for neonatal heart rate segments. For prospective classification of FHR patterns a moving discriminant function was introduced.     

Fetal behavioural states in epileptic pregnancies

Possible negative effects of maternal antiepileptic medication on fetal motility and heart rate patterns were examined at 32 and 38 wk of gestation. Fetal eye and body movements were recorded using 2 real-time ultrasound units. Comparison between pregnancies with antiepileptic medication and control pregnancies did not show marked differences in patterns of motility and heart rate. Duration of sleep states, occurrence and duration of body movements in state 2F and statistical parameters of heart rate level and heart rate variability were very similar for both groups. This preliminary study, limited to mostly combined treatment with antiepileptic drugs, could not demonstrate any obvious effect on fetal neuromuscular development from maternal antiepileptic medication.     

Assessment of fetal lung development by quantitative ultrasonic tissue characterization: a methodical study

OBJECTIVES: This study was performed to evaluate the quantitative ultrasonic tissue characterization of the normal fetal lung development by using acoustic raw data captured after preprocessing. METHODS: One hundred and sixty-two patients with completed gestational ages between 22 and 37 weeks were enrolled in this study. Longitudinal and transverse sections of the fetal thorax and upper abdomen were imaged. A region of interest of constant size was defined and the tissue-specific gray scale was determined by using an interactive software. RESULTS: A total of 162 patients met the inclusion criteria. The echogenicity of the fetal lung showed a particular changing pattern during pregnancy: the mean gray value of the fetal lung (MGV) is almost the same as the MGV of the fetal liver at 22 and 23 weeks, decreases between 22 and 31 weeks and increases between 31 and 37 weeks. The MGV of the fetal liver decreases significantly from 24 weeks to 31 weeks and increases significantly again toward 37 weeks. We stated that the MGV of the lung is smaller than the MGV of the liver during 31 weeks of gestation and the relation reverses in late gestation. At term, the MGV of the liver is greater than the MGV of the lung. The lung-to-liver ratio is <1 between 24 and 29 weeks and >1 between 30 and 35 weeks. CONCLUSION: The echogenicity of the fetal lung showed a particular changing pattern during pregnancy, which corresponds to morphologic changes of the fetal lung development.     

Fetal behavioural states and hypertensive pregnancy.

Delay in fetal maturation in diabetic and accelerated fetal maturation in hypertensive pregnancies have been reported in the past. The spontaneous activity of fetal nervous system during pregnancy was followed longitudinally in a group of 29 normal pregnancies from 28 x th to 40 x th week of gestation by means of fetal behavioural states determination. 1 F state (quiet sleep) progressively increases from median values of 5.0% to values of 22.5-25% at term of pregnancy. This state represents the positive activity of inhibitory centers has been related to a positive evolutionary process of brain maturation according to preceding experiences conducted on experimental models and preterm babies followed with EEG and direct observation in the early neonatal period. The method of behavioural states determination has been applied to a group of 33 gestational diabetes (GDM) pregnant women followed longitudinally, and a clear reduction of development of 1 F state has been evidentiated, with significant differences (p less than 0.001) at 35-36 weeks of gestation versus the control group. The normal values are reached in concomitance with L/S value of maturity. In 30 pregnant women affected by gestational hypertension (GH) different result are obtained: 1 F state seems to develop earlier, and is increased (p less than 0.001) around 30-32 weeks versus the control group if a fetal growth reduction is present. The value of 1 F behavioural state in the evaluation of fetal condition of pathological pregnancies is discussed.     

The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relation to fetal behavioural states in normal pregnancy at 37-38 weeks

The relation between the blood flow velocity waveform in the fetal internal carotid artery (n = 12) and umbilical artery (n = 15) and fetal behavioural states at 37-38 weeks of gestation was studied. In the fetal internal carotid artery, under standardized fetal heart rate conditions, the pulsatility index (PI), as a measure of peripheral vascular resistance, was significantly lower during behavioural state 2F (active sleep) compared with state 1F (quiet sleep) according to the classification by Nijhuis et al. (1982), suggesting increased fetal cerebral blood flow during state 2F. In the umbilical artery, no significant difference in PI between the two behavioural states could be established. This suggests a fetal origin of the state dependency observed in fetal blood flow velocity waveforms.     

The ultrasonic demonstration of fetal abnormalities in utero.

The demonstration of fetal diseases and anomalies in utero can now be performed with a high degree of accuracy with modern ultrasonic equipment. This paper describes the more common and important fetal anomalies which can be demonstrated by ultrasound and indicates the importance of meticulous attention to technique and the significance of the acquistion of skill in real-time sonography by the physician-sonologist. The thoroughness of all obstetric sonographic examinations is emphasized to enable detection of unsuspected fetal anomalies. Specific methods to demonstrate these anomalies in the high-risk patient are also described. Several pitfalls in the diagnosis of fetal disease in utero are included which show the nonspecificity of some of the ultrasonic signs.     

The ultrasonic Doppler fetal actocardiogram and its computer processing

Gross fetal movement was detected using a lower frequency ultrasonic Doppler shift than that used in the study of fetal heart action. The movement signal was changed into deflection which was recorded on CTG chart simultaneously with the fetal heart rate (FHR), and was called the fetal actocardiogram. Visual analysis of the actocardiogram showed bursts of active fetal movements in the active fetal state which were concordant with acceleration of FHR. The analysis was useful in the study of fetal behavioural states. Imminent fetal distress produced a loss of FHR acceleration which was accompanied by a burst of fetal movement, i.e. a true non-reactive state of the FHR. The output of the actocardiograph was analysed using a PC98XA computer with a simple statistics of deflection amplitude and interval, displayed as 3-dimensional histograms of the number and frequency, and the formation of the envelope curve of the deflections. The study demonstrated that it is possible to recognize fetal behavioural states automatically. This includes active and resting fetal states as well as fetal breathing movements.     

The accuracy of ultrasonic measurement of fetal crown-rump length

Routine ultrasonic crown-rump length measurements were retrospectively evaluated in an antenatal clinic using maternal body temperature graphs as reference to ovulatory age. A comparison with the original figures of Robinson is made. Potential errors are discussed. The conlusion is that one should be very careful in interpreting an ultrasonic CRL measurement before 10 weeks menstrual age because of both measurement and operator errors.     

Evaluation of fetal movements with ultrasonic Doppler fetal actograph

Fetal movements in each trimester were recorded objectively and continuously with an ultrasonic Doppler actograph that enables simultaneous tracing of fetal heart rate (FHR) and fetal movement (FM). The record with this method was compared with those of the ultrasonic B-mode and M-mode respectively. The onset of FM signal bursts and FHR acceleration was nearly synchronous and the transitory FHR increase associated with FM signal bursts showed a linear amplitude increment along with the progress of gestation. Fetal hiccup movements were recorded from 24 weeks of gestation and lasted between 4.3 minutes and 17 minutes with a rate of 25 to 28 per minute. No FHR acceleration was recognized in such movements. Maternal perception was 67.7% on average of FM signal bursts. Fetal movements in early pregnancy were detected in the 11th week of gestation (CRL 54 mm). Long-term recording of fetal movements was carried out between 9:30 and 17:00 and the alternation of active and resting phases was investigated. The resting phase lasted 20 minutes on average, (range, 10 to 36 minutes). The fetal activity was not influenced by the maternal food intake. It is clinically significant to evaluate the change in fetal movements objectively and continuously.     

The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relation to fetal behavioural states in normal pregnancy at 37–38 weeks

Summary. The relation between the blood flow velocity waveform in the fetal internal carotid artery ( n = 12) and umbilical artery ( n = 15) and fetal behavioural states at 37–38 weeks of gestation was studied. In the fetal internal carotid artery, under standardized fetal heart rate conditions, the pulsatility index (PI), as a measure of peripheral vascular resistance, was significantly lower during behavioural state 2F (active sleep) compared with state 1F (quiet sleep) according to the classification by Nijhuis et al . (1982), suggesting increased fetal cerebral blood flow during state 2F. In the umbilical artery, no significant difference in PI between the two behavioural states could be established. This suggests a fetal origin of the state dependency observed in fetal blood flow velocity waveforms.     

Impaired fetal growth: ultrasonic evaluation and clinical management

Although biparietal diameter has become the standard fetal dimension for dating purposes, it is accurate in the diagnosis of intrauterine growth retardation in only 50% of cases. Serial assessment of the abdominal circumference, on the other hand, may allow more accurate identification of impaired growth. The combined use of biparietal diameter and abdominal circumference in the estimation of fetal weight in utero directly addresses the basis of the diagnosis of impaired fetal growth. Ultrasonic observation of amniotic fluid volume, fetal muscle tone, and the texture of the placenta may also be valuable in the diagnosis of intrauterine growth retardation. Once a diagnosis of impaired fetal growth is made, the clinical management includes, possibly, treatment of maternal factors that may be contributing to the growth retardation and monitoring of fetal and maternal well being with delivery if serious deterioration of either mother or fetus is noted. Maximal safe retention in utero is the management goal, as long as some growth is noted and acute distress is not seen.     

Fetal macrosomia as an important indicator of fetal malformation syndrome: ultrasonic findings of two cases

Two extraordinary cases of fetal macrosomia are presented. It is discussed that extreme fetal growth should raise the suspicion of a malformation syndrome and deserves thorough antenatal ultrasonographic examination.     

Accurate ultrasonic estimation of fetal weight

The accuracy of eight ultrasonic fetal weight formulas were analyzed in 1099 fetuses who underwent real-time ultrasound examination within 72 hours prior to delivery. Shepard's formula was most consistently found to give the lowest systematic and random errors throughout all weight categories, though Deter's formula had an almost identical accuracy. The Shepard formula was further analyzed in respect to the effects of fetal sex and birthweight centile grouping on the accuracy of fetal weight estimation. The results indicated that fetal sex had no effect on the accuracy of fetal weight estimation, but that birthweight centile grouping did. The weights of small-for-gestational age infants were systematically overestimated, while the weights of large-for-gestational age infants were systematically underestimated.